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Re: Tinnitus and a dip in the audiogram

If I understand you correctly then a problem with this idea is that the medial efferents don't stimulate the outer hair cells and drive more amplification, but reduce it - the MOC efferents make up a negative feedback loop.


Date: Tue, 11 Sep 2012 10:30:38 -0500
From: flatmax@xxxxxxxxxxx
To: markfletcher22@xxxxxxx
Subject: Re: [AUDITORY] Tinnitus and a dip in the audiogram

Yes I think you are on the right track ...

The link below is an article which discusses emissions in Tinnitus patients ... I have another link somewhere (can't find it now) which actually shows spontaneous emissions @ tinnitus frequencies.



On 09/11/2012 10:13 AM, Mark Fletcher wrote:
It's an interesting idea. Would you not expect to see evidence for this in otoacousitc emission work in tinnitus patients (I don't know if you do or not)?


> Date: Mon, 10 Sep 2012 10:03:24 -0500
> From: flatmax@xxxxxxxxxxx
> Subject: Re: [AUDITORY] Tinnitus and a dip in the audiogram
> To: AUDITORY@xxxxxxxxxxxxxxx
> Your second point here is one I like. However it may also be the same as
> your first point :)
> Our mixed-mode Cochlear amplifier supports your hypothesis.
> http://adsabs.harvard.edu/abs/2011AIPC.1403..611F
> The general idea is that certain types of Cochlea damage enhance the
> peripheral hearing circuit.
> For example, consider this thought experiment based on our mixed-mode
> Cochlear amplifier model :
> Imagine that your stereocillia are lopped off in a small region of inner
> hair cells - the same can be said for outer hair cells. This may happen
> due to ageing or damage.
> In this case assume that the stereocillia resistance is reduced - due to
> gaping open ion channels - and ionic currents into the cell (potassium)
> and our from the cell (sodium) are enhanced ... the hair cell now
> experience a depolarisation. This depolarisation generates more
> spontaneous neurotransmitter release.
> The neurotransmitters generate more synaptic transmission in the
> cochlear nerve.
> The cochlear nerve excites the superior olive and this not only
> generates perception of the tone, but sends signals back to the Cochlear
> over the lateral and medial efferents.
> The medial efferents stimulate the motors in the outer hair cells and
> they in turn generate movement at the inner hair cells which start the
> process again ... over and over again ... the end result is a
> mecho-neural standing wave ... or 'tinnitus'.
> This type of tinnitus masks low level sound heard through the ear ...
> however if the external sound gets loud enough, then it masks the tinnitus !
> What do you think ?
> Matt
> On 09/10/2012 08:22 AM, Matt Winn wrote:
> >
> > Mark and everyone,
> >
> > Although I am not a tinnitus researcher, I have had lots of experience
> > with patients with tinnitus in the audiology clinic. Generally, we try
> > to avoid the confusion of tinnitus with testing tones by using pulsed
> > and/or warbled tones. As you point out, this doesn’t always work out
> > perfectly.
> >
> > It has been my experience that dips in the audiogram are indeed
> > frequently accompanied by tinnitus. having measuring hearing at the
> > VA, this connection might be limited to hearing loss that is
> > noise-induced. The two most common explanations I have heard for this
> > are 1) damage to the auditory system at the site of the hearing loss
> > underlies both the threshold elevation and improper firing by damaged
> > nerves, and 2) tinnitus that exists in the region of the dip is not
> > masked out by external stimulation because the external sounds are
> > less audible; thus rendering tinnitus more noticeable. This latter
> > explanation accounts for the relief from tinnitus experienced by many
> > people who use hearing aids. Specifically, tinnitus isn’t “cured,” but
> > it is masked out by the amplified input, and then the tinnitus returns
> > after the hearing aid is removed.
> >
> > Returning to the point of tinnitus without apparent hearing loss, I
> > have found that salt intake and stress level are two (among many)
> > contributing factors to and my own tinnitus, and I don’t have hearing
> > loss. The dependence of OHCs on metabolic factors underscores this
> > connection, which seems anecdotally to be exacerbated in patients with
> > Ménière’s.
> >
> > Matt
> >
> >